To continue the follow-up of 240 patients studied for cerebrovascular insufficiency (transient ischemic attacks) during the past ten years. To develop new methods for evaluation and screening of patients who have transient ischemic attacks particularly Doppler carotid scanning, ocular plethysmography, and regional cerebral blood flow studies. To initiate neuropsychological studies on patients with cerebral circulatory insufficiency. To assess transient ischemic attacks as a risk factor for cardiac death. To carry out studies of regional cerebral blood flow and intracranial pressure in patients with acute strokes and head injury. To improve laboratory models for cerebral vascular disease by (a) selective breeding of the gerbil to increase the incidence of anomalies in the circle of Willis. To develop a primate model for cerebral atherosclerosis.